After being removed from the body of the animal, a skin has one side called the "hair side", and its other side is called the "flesh side" and retains residues of flesh and fat together with numerous blood vessels. Such raw skins which are non-negligible in size and weight need to be subjected to various treatment operations during which numerous manipulations are necessary before they are transformed into leather.
One of these operations concerns treatment methods intended to conserve the skins, and the most commonly used technique is that of salting a stack of raw skins.
After the skins have been roughly cleaned on the flesh side, this salting technique consists in stacking the skins flat, flesh side up, and salting the flesh side of each skin prior to laying the next skin on top of it. This technique gives rise to stacks of skins that may be 1 meter (m) to 1.50 m high, which stacks are conserved in this state for the length of time required to dehydrate the skins so as to prevent or stop the development of microbes.
Experience shows that the conditions under which skins are salted and stored have a very large influence on the state of the conserved skins. Thus, during conservation, numerous well-known blemishes may occur such as pitting of the flesh side or the grain side, red or violet spotting, sweating, and/or arbor-escences. These blemishes or defects all have repercussions on the quality and appearance of the resulting leather.
It appears that salting and storage are not always performed under the best possible conditions, particularly insofar as these operations can be difficult for the handling personnel whose job it is to make up the stacks. The skins must be unfolded completely to lay them out flat giving rise to awkward and wearisome manual handling opertions because of the size, the weight, and the greasy nature of the skins, and also because of the heights of the stacks to be built up.
Another skin treatment operation, likewise requiring handling operations, concerns the technique of cropping. This operation consists, after the salt covering the skins has been removed, in cutting up each skin into four parts, namely the butt, the shoulder, and two belly parts. To this end, the handling personnel need to grasp the skins and shake them in order to remove the salt from the skins. Thereafter, the personnel fold each skin along the line of greatest back thickness corresponding to the portion of the skin that overlayed the spinal column of the animals, so as to enable both belly portions of the skin to be cut off simultaneously.
It is clear that taking hold of, grasping, and folding skins constitute operations which are difficult and wearisome for skin-handling personnel given the size, the weight, and the slippery nature of skins. In addition, it is difficult to fold skins in two along the line of greatest back thickness, and if the folding is poorly done, subsequent cutting will be inaccurate and erroneous relative to the portions of the skins thus obtaining portions of leather that are not uniform in structure.
When the two treatment operations described by way of example are analyzed, it can be seen how manipulation operations have an effect on the appearance of the final leather. There therefore appears to be a need for means for handling skins or hides in the various treatment operations to which the skins or hides are subjected, with "treatment" being taken in a general sense.
German patent application DE-A-24 07 665 describes an apparatus for handling skins prior to an exchange operation. The apparatus described includes two pincers each connected to a cable which is intended to be wound onto a drum whose rotation is controlled. The pincers are intended to hold the skin by its legs.
Although using such an apparatus provides a degree of help for the personnel handling skins, practice shows that such apparatus is unsuitable for spreading skins out completely flat insofar as the skins are handled via their leg portions. The problems relating to the salting technique therefore remain intact. In addition, the apparatus is not at all well adapted to the cropping technique.
The object of the present invention is therefore to provide a novel method suitable for handling skins or hides during various treatment operations while relieving handling personnel from the various constraints they are subject to and eliminating the causes of skin or hide deterioration.
The invention seeks to provide a method of storing skins in stacks which is suitable for limiting blemishes or defects due to storage.